1. Field of the Invention
The present invention relates to a reflected pattern-printed transparent sheet which is a member capable of being applied to a data input system inputting onto a picture plane of a medium, having a light weight and a low price, easily increased in an area and providing a coordinate (position information) detect means capable of being produced in a large quantity and in which a strong reflected light is obtained.
2. Related Art
In recent years, increased is necessity to convert handwritten characters, pictures, marks and the like to electronic data which can be handled by information processing devices, and in particular, increased is demand to systems in which handwritten informations are input into a computer and the like in real time without passing through a read device such as a scanner and the like.
In order to meet the above situations, it is consider to combine, for example, an electronic pen with a matter on which patterns reflecting a non-visible light are printed as position information showing positions of input lines.
Disclosed in, for example, a patent document 1, is a transparent sheet which is mounted on a front face or a front side of a display device and on which marks capable of providing position informations for showing the positions of input lines by an electronic pen for input and the like are printed by using an ink emitting light capable of being read by the above input line read means by irradiating with light having a prescribed wavelength.
Further, a coordinate input device prepared by using a transparent member on which a specific ink reflecting light in an infrared region is printed is disclosed in a patent document 2.
However, the examples of specific transparent sheets are not shown in the patent documents 1 and 2, and only an idea or a desire of a transparent sheet is described therein.
On the other hand, disclosed in patent documents 3 and 4 are diffraction gratings comprising a color filter of LCD using a cholesteric liquid crystal layer or a liquid crystalline film in which diffraction patterns are transferred on a chiral smectic C liquid crystal layer, circularly polarized plates, optical filters and the like.
However, in the techniques disclosed in the above documents, it is not indicated to make use of the above liquid crystal layers for dot-like patterns for detecting coordinates. The above liquid crystal layers are thin, and when it is assumed to read them by means of a pen type sensor which reflects an infrared ray and detects a reflected light thereof in the form of an image, it has been difficult to obtain an intense reflected light.
Accordingly, a reflected pattern-printed transparent sheet having a high reflection intensity of an infrared ray or a UV ray is desired.    Patent document 1: Japanese Patent Application Laid-Open No. 256137/2003    Patent document 2: Japanese Patent Application Laid-Open No. 243006/2001    Patent document 3: International Patent Publication WO99/034242 pamphlet    Patent document 4: Japanese Patent Application Laid-Open No. 154865/2006